Re: Direct Sampling frequency limit in r 1628 onwards #sdrsharp #spyserver


jdow
 

The guts of the dongles don't really allow tuning higher than 14.4 MHz. For that matter 14.4 MHz may be rather pushing the RTL chip, the one which performs IF filtering and A/D conversion.

{^_^}

On 2017-11-21 10:05, Martin via Groups.Io wrote:
[Edited Message Follows]
Hi,
I see that in the release notes for r 11628 onward that "Set RTL max frequency to 14.4 MHz in direct sampling mode." has been added.
Is there any particular reason for this ?
I understand the desire use the tuner chip as much as possible in order to avoid Nyquist Alias signals and to have RF gain control. But I have an application where I wish to continue using direct sampling above 14.4MHz and this change has caused problems for me.
Could I suggest that it may be better if the user / admin could set this as required, as some configurations may need to use direct sampling above 14.4MHz and others may not.
It would be even better if it was possible to define frequency limits for direct / quadrature sampling in SDR Sharp and Spyserver, so that this could change automatically when the defined frequency boundary is crossed. This would save having to reconfigure things manually for example when you wish to move from HF to VHF and allow a mix of HF / VHF / UHF frequencies to be scanned.
It may also be possible to extend this proposed configuration option to automatically turn spyserver on-off (along with the frequency off-set) or turn the bias tee on / off (if folks are using this to switch antennas or pre-amps in / out).
Regards,
Martin - G8JNJ

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